Automatic draft control



June 21, 1932. a. VALJEAN 1,364,223

AUTOMATIC DRAFT CONTROL v Filed Sept. 19, 1929 Patented June 21, 1 932 UNITED STATES.-

AUTOMATIC DRAFT CONTROL Application filed September 19, 1929. Serial at. 393,636..

My invention has to do with the automatic control of a variable draft upon a burner wherebytoefi'ect and maintain a substantially uniform supply of air to the burner, not-- withstanding repeated and even violent fluctuations in the draft due to high wlnds, un-

equal combustions or other causes.

Not specifically does my invention supply a need in connectionwith fluid fuel burners,

1 oil or gas, but is also adapted to solid fuel burners.

In the accompanying drawing and description the invention is set forth in detail as applied to an oil burner by way of example.

In the drawing,

Fig. 1 is a vertical section through the lower portion of an oil burning water heater equipped with my improved draft control;

Fig. 2 is a front elevation of the draft con- :0 trol;

Fig. 3 is a vertical section on the line 3-3 of Fig 2; and

Fig. 4 is a similar section through a mothfication.

26 Referring to Fig. 1 of the drawing, a typical form of water heater is represented having an outer casing 11 and an inner casing Band with interposed insulating material 13. The water chamber 14 surrounds a centrally disposed combustion chamber 15, the

lower portion of which is in open communication with the neck 16 of an oil burner 17 of the carbureter type such as that set forth in my Patent No. 1,512,869 and described as to. operation more particularly in my Patents Nos. 1,280,596 and 1,639,202. The burner 17 is enclosed within a housing 18, theonly admission of air thereto in substantial amount being by way of an air chute 19, the entrance 20 to which is controlled by the automatic mechanism forming the subject of the present invention and which will hereafter be described in detail.

The burner is supplied with fuel through fuel supplypipes 21 and 22 having interposed therein a front chamber 23 of appropriate construction.

Having reference to Figs. 2 and 3, it will be observed that the entrance to the air chute 19 is generallyrectangular in shape with an P NT BEN vanman, or LANSING, micmenn, assrenoa TO moron wnnm. conrona'rrom'or Lmsme; mrcnrean, A coarona-rrou or nrcmeau fipw'ar lp jecting arcuate lowe -.Wall 5,,Iwiths'u stantially vertical parallel 115. M Hinged in the side wall .1of., the opening 20 upon ahorizont'al pivq 2'Z'isra blade 28 which preferably comprises two ofii'set porti0ns 28 and 28? arranged at oblique angles one to the other, as, clearlyishown in Fig. 3. By gravity the blade hangsin the position shown in full lines in said figure',thus leaving space between said blade and the .walls of the chute at each side and below; Under the influence of normal draft, the blade will be caused to swinginwardly, as shown in dotted lines, to a position where the space is closed off between the blade and the side walls 26 of the chute,"leaving' only space between the lower edge of the blade'and the curved bottom wall 25. c p It will be observed that the c" vature-of the bottom wall 25 is on a radius about'a point outwardly and upwardly beyond the pivot 27, with the result that the arc traversed by the lower edge of the bladeis eccentric to the arc of the lower wall 25, andconsequently the air space between the lower edge of the blade and the wall 25; progress si'velydecreases as the blade'swings inward- 1y to almost a vanishing point at 29. when blade reaches a stop against wall 24. Y 1 In operation, where there is no draft upon a cold burner, the blade 28 will han freelyf- 5 I as indicated in full lines in Fig. 3. the a; a

draft is induced by the lightin ofa firewithin the burner, the pressure 0 the air upon the blade 28 will cause the same to swing in'" wardly, gradually cutting off the admission of air as the draft increases until a bal anced condition is reached. In normalop ,eration of the burner, this balanced draft stage having been reached, the blade of the damperwill remain in asubstantially con stant position subject only to a slight vibration to compensate for any inequalities of 9 combustion or change in chimney draft due V to a high wind. It will be observed that at the outset, the admission of air to the chute is quickly reduced as the damper blade starts to swing inwardly, and as the air passage at" 1 a ases 1w" the side of the blade is cut off and that thereafter the variations in the air supply .are much less pronounced, gradually increasing as the natural draft decreases and decreasing s as the natural draft increases so as to maintain a substantially uniform supply of air to the burner under all conditions. 7 p

In Fig, 4 a more simple form of the inven tion is shown wherein the blade 30 pivoted at m 31 hangs by gravity within the chute and closely adjacent the side walls 32. Here, as

in the former case, the curvature of the bottom wall 33 of the chute is eccentric to the arc 3 f traversed by the lower edge of the 15 blade 30. The operation is substantially the same as that previously described save that the ratio of change in the air passage is substantially constant, without the rapid initial change. I

go I claim:

1. The combination with an oil burner and a substantially sealed housing there-. for having an air inlet chute of gradually decreasing cross-sectional area, of a draft con- 25 trol device comprising a blade offset to lie in oblique planes and hinged at the upper side of the chute entrance and free to swing into said chute under pressure of the draft, the side walls of the chute cut awa over an area including the oblique planes whereby the air inlet area is varied inversely withv the draft but in decreasing proportion as the draft increases. a

2. The combination with an oil burner and 35 a substantially sealed housing therefor having an air inlet chute with parallel side walls and with a lower wall curved inwardly and 7 Q upwardly, ofa draft control device comprising a blade offset to lie in oblique planes and 40 hinged at the upper side of the chute entrance and free to swing into said chute under pressure of the draft, the arc traversed by the lower edge of the blade being eccentric to that of the curved lower wall, whereby the 5 air inlet area is varied'inversely with the draft in irregular decreasing proportion as the draft increases. V 3'. The combination with an oil burner and a substantially sealed housin therefor 5 having an air inlet chute of re ually decreasing cross sectional area, 0 a draft control device comprising a blade offset to lie in oblique planes and hinged at the upper side of the chute and free to swing into said 5 chute under pressure of the draft, the side walls of the chute cut away over an area' including the oblique lanes, whereby the air inlet area is varie inversely with the draft first rapidly but in decreasing proporw tion as the draft increases.

In testimonywhereof I have hereunto subscribed my name. 7 7

-' BEN VALJEAN. 

